In the paper you also wrote

With the brain, by contrast, it’s not nearly so obvious that the “Knightian indeterminism source” can be physically swapped out for a different one, without destroying or radically altering the brain’s cognitive functions as well.

But given the relatively large amplitude of the microscopic thermal noise that CellBioGuy points to, what evolutionary reason would favor a strong role for quantum freebits? After all, thermal noise is far beyond the comprehension of any rival or predator organism. So the organism is safe from being too predictable, even if it harnesses only probabilistic randomization sources. Or it might amplify both types of randomness, thermal noise and quantum freebits alike. But in that case I'd expect the thermal noise to dominate the cognitive and behavioral results, just because thermal noise is so richly available.